The nex-7 seems really attractive to me but I wonder if you will really be able to take advantage of the 24mp on the sensor. With the 5dII I find that I have to shoot at x2 the focal length to get sharp images handheld -- I imagine it would be a much bigger problem given the greater pixel density.
I'm not sure there should be a bigger problem if both cameras (full frame and cropped-format) have similar pixel count. Not much difference between 21mp and 24mp.
If you find that you need a shutter speed of 1/2FL with the 5D2, then the same requirements should apply to a 24mp cropped format, provided the FL figure used is the FF 35mm equivalent
, ie. 1/160th with an 80mm lens on the 5D2 becomes 1/160th with a 50mm lens on the cropped format, both situations providing the same FoV and the same resolution of image (approximately).
Nevertheless, as pixel count increases, faster shutter speeds are required for the larger images or prints that are possible. A base ISO of 200 is really nice. Both my Nikon D700 and Canon 50D have a base ISO of 200.
However, there's no free lunch. My D7000 at its slower base ISO of 100 provides significantly greater dynamic range than the D700 and 50D at ISO 200. Even at ISO 200, the D7000 provides 0.75 stops greater DR than my D700 and a whopping 1.5 stops greater DR than the 50D.
Since the D7000 uses a Sony sensor, I'd be surprised if the DR at ISO 200 in these new cameras were not better than the DR of the 5D2 at its base ISO of 100, although the 5D2 should still have lower noise at 18% grey because it's a full frame format.